This invention relates to a semiconductor device having an interlayer insulating film, such as, a SOG (Spin on Glass) film and a method of manufacturing the same.
Recently, a semiconductor integrated circuit has a trend in which a size thereof has been reduced. In particular, this trend is remarkable in a field of a multi-layer type wiring in a logic circuit.
As a distance between metal wiring patterns is reduced in the field of the above multi-layer type wiring, a cross talk often takes place between metal wiring patterns adjacent to each other. Herein, it is to be noted that the above-mentioned cross talk means that a wiring signal on one wiring pattern transfers to the adjacent wiring pattern.
In order to avoid the cross talk, it is effective to use an interlayer insulating film having a low dielectric constant. To this end, a variety of materials for the interlayer insulating film have been developed to apply them in the field of the above multi-layer type wiring.
Among the above materials, great attention has been paid for a hydrogen silsesquioxane (thereinafter, abbreviated as an HSQ) polymer as the interlayer insulating film, such as the SOG film. In this event, the HSQ film contains a plurality of Si--H bonds and has a porous structure.
When the semiconductor device is fabricated by using the HSQ as the interlayer insulating film, a through hole or a via hole is formed in the interlayer insulating film of the HSQ. In this case, the through hole is formed in the interlayer insulating film by the use of a photo-resist.
After the through hole is opened, the photo-resist is generally removed by an O.sub.2 plasma process and a subsequent wet process.
As mentioned before, the HSQ insulating film has a plurality of Si--H bonds. These Si--H bonds are exposed to the above-mentioned O.sub.2 plasma process at the surface of the HSQ insulating film in the through hole. In consequence, the Si--H bonds are reduced and changed into a Si--OH bond through the above-mentioned O.sub.2 plasma process. This fact is disclosed in Proc. of the 43rd Symp., Applied Physics, p654, 26a-N-6 (April 1996).
As a result, the HSQ insulating film absorbs moisture in the subsequent wet process. Under this circumstance, when a via plug is formed in the through hole, a poisoned (e.g., contaminated) via is often formed in the via plug. This poisoned via makes the through resistance abnormal. In addition, the dielectric constant of the HSQ insulating film becomes unstable.
Thus, the conventional semiconductor device has a problem in which the HSQ insulating film absorbs moisture through the above-mentioned O.sub.2 plasma process to cause the abnormality of the through resistance. This is because the Si--H bond at the surface of the HSQ insulating film in the through hole is changed into the Si--OH bond through the O.sub.2 plasma process.